* fix(metadata): add BadRequestException for 4.3

src/Mcp references ApiPlatform\Metadata\Exception\BadRequestException,
which only existed from 4.4 on. The 4.3 MCP jobs passed only because
#8522 had pinned the metadata sibling to ^5.0@alpha; with the correct
^4.3 constraint restored they fail with "Class not found".

Copied verbatim from 4.4 so the merge-up is a no-op. Fixes the 6
api-platform/mcp jobs (2 errors each) and PHPStan (4 errors).

* fix(mcp): update tools/list schema expectation

#8522 rewrote array `type` nodes into anyOf branches in
Mcp\JsonSchema\SchemaFactory (see #8504) but left McpTest::testToolsList
asserting the old `type: [string, null]` shape, so it was merged red.

This single assertion accounts for the failure in all 11 PHPUnit jobs
on 4.3.